Electrical Test
lnstruments MAC-20 Retrofit Package
Section lll
-
Operating
lnstructions
SINGLE POLE MOLDED CASE CIRCUIT
BREAKERS
Timing Test
1. Consult breaker manufacturer's literature to determine any necessary
precautions
and expected test results. A test current of three times the rating
of
the breaker
should be used for this test.
2. Follow steps 1 through 18 in
general
test
procedures,
as
required,
to set up the
breaker test set.
3. Setup MAC-20 for C.L. MOM.
4. Set
MAC-20
RANGE to
lowest range
that is
greater
than desired test current.
5. Set
TIMEBASE
to CYCLES.
6. Press
PRESET
key. Adjust
preset
time to
2.0
cycles.
7. Press PRESET again to return to normal mode.
8. Select
MEMORY mode.
9. Repeatedly
jog
the INITIATE button,
while
adjusting the
OUTPUT
CONTROL
higher, until the
desired test current is read on the ammeter. lf insufficient current is
obtained
at maximum
position
of the
vernier,
set the
OUTPUT TAP control to
the
next
higher tap, return the vernier to zero, and continue.
10. Press RESET button.
1 1. Set
TIMEBASE to SECONDS.
12. Select LATCH mode.
'13.
Press and release INITIATE key; CLOSE
or
OUTPUT
ON light should
glow,
timer
should run, and current
display should read desired output current.
14. While test is running, observe
current reading. lf necessary, adjust to correct
value
by using vernier control.
15.
When breaker trips, the test set output should
de-energize, timer should stop,
CLOSE or OUTPUT ON
light should turn off, and
TRIP
or OUTPUT
OFF light
should
glow
(lf
applicable).
16.
Read and record trip
current and trip time. Compare to
manufacturer's time/current
curve.
lf test is to be repeated,
make sure that
breaker cools completely.
Shut
down test set, disconnect
breaker,
and
prepare
for subsequent testing or
relocation
according to steps
20 through 25 in
general
procedures
outlined above.
Electrical
Test lnstruments, lnc.
Page lll-4
17.
18.
Copyright(C)
1994-1998
All Rights Reserved
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